Root Access

8:09 PM

@rahuldottech You need long/lat/alt. For arbitrary locations on Earth, it's traditionally with double-precision floating point numbers (24 bytes total).

Though single-precision floating point is enough to store coordinates that are accurate to tenths of a second.

That Brazilian Guy

I'm bored.

I just took a 20km train ride to buy RAM.

And now taking the ride back.

bwDraco

> 20km

ow.

That Brazilian Guy

40min by train

And then 10min by car

That, or pay 25% more for the RAM

bwDraco

Yeah, had a bit of a brain fart, thought I made a mistake. You can be accurate to less than 8 ft.

You could express longitude and latitude internally as signed 32-bit ~~integer~~ fixed-point decimal numbers and this problem would disappear, but additional (albeit simple) processing would be necessary.

The altitude would need to be single-precision floating-point.

With fixed-point numbers, you'd get the full 32 bits of precision around the Earth (the sign bit is used for direction, but that's 31 bits for each half of the Earth).

But you'd have to multiply the value by 180 (latitude) or 90 (longtitude) and use floating-point numbers for this computation before a human-readable coordinate can be displayed to the user. Double-precision floating-point numbers would be required to avoid loss of precision.

That's trivial to do.

This storage format would provide precision better than three-eights (3/8) of an inch, which is far more precision than is required for most applications.

djsmiley2k

8:34 PM

@bertieb the skys here are amazingly clear tonight

can't see any yet tho

bwDraco

Floating-point numbers for latitude would result in progressively worse precision towards the farther you are from the Prime Meridian.

Horn OK Please

wifi

bwDraco

There would only be 17 bits of precision (about 1,000 ft) past either 128th parallel, because 7 of the 24 bits in the mantissa would be needed to store the integer portion of the latitude value.

Actually, 16 bits. Sorry.

Correction: With single-precision numbers for latitude, there would only be 16 bits of precision (about 1,000 ft) past either 128th parallel, because 7 of the 23 bits in the mantissa would be needed to store the integer portion of the latitude value.

(getting confused about the implicit bit in the IEEE 754 format)

Eight bits, including the implicit bit, or seven bits as stored in the mantissa field.

djsmiley2k

@bwDraco you don't need alt.

he's hardly going to be beneath the earth or floating on top

long and lat is all.

bwDraco

8:49 PM

@HornOKPlease (or another room owner), can you move this and this to trash?

With single-precision numbers for latitude, there would only be 16 bits of precision (about 2,000 ft) past either 128th parallel, because 7 of the 23 bits in the mantissa would be needed to store the integer portion of the latitude value.

(I keep second-guessing myself)

djsmiley2k

when you return to a game after a while annd have no clue what you're doin

bwDraco

Open Location Code

The Open Location Code (OLC) is a geocode system for identifying an area anywhere on the Earth. It was developed at Google's Zürich engineering office, and released late October 2014. Open Location Codes are also referred to as "plus codes". Open Location Codes are a way of encoding location into a form that is easier to use than showing coordinates in the usual form of latitude and longitude. They are designed to be used like street addresses, and may be especially useful in places where there is no formal system to identify buildings, such as street names, house numbers, and post codes.Open...

OLC ("plus codes") has the advantage of human readability and scalable precision.

But obviously, needs a lot more processing to generate.

Enough about computer representations of coordinates. I spent nearly an hour going down this rabbit hole.

djsmiley2k

And you learn possibly more in that hour about coordinates, than you have in weeks of trying to learn docker?

bwDraco

lol yup.

djsmiley2k

9:05 PM

find a rabbit hole which is the path you want to learn

and learning becomes much easier

bwDraco

Also, TIL that when you have a bounded range of values, fixed-point is better than floating-point.

@djsmiley2k Also, part of the reason for these problems is that I've lost sight of the original goal I had when I first got the book.

DavidPostill

:(

Harry is 1 hat in front of me

djsmiley2k

@DavidPostill anything we can do to help?>

bwDraco

usatoday.com/story/travel/flights/2018/12/13/… WAT

> a life-critical cargo shipment [...] intended to stay in Seattle for delivery to a local hospital.

Seriously?

DavidPostill

9:22 PM

@djsmiley2k No :/

bwDraco

9:38 PM

Just got this:

amazon.com/dp/B072V5NXPY

Looking at the manual, it looks like it can indicate what codec is being used (every 5 seconds: one blue flash for SBC, two blue flashes for FST [Avantree proprietary FastStream codec], one white flash for aptX, two white flashes for aptX Low Latency).

This thing transmits at a pretty low volume. I have to turn up the MP3 player to a very high volume in order to get reasonably loud audio on my Sennheiser PXC 550 Wireless headphones.

(probably because it's originally designed for transmitting TV audio)

Then again... it does appear to support Bluetooth absolute volume control as it's retaining the volume set at the headphones when I power-cycle it, independent on the headphones' own internal volume setting (used when connected by the audio jack or to a device that does not support absolute volume control)

So this seems to be perfectly normal.

Horn OK Please

9:53 PM

TIL that enabling MU-MIMO on my wifi router (it's enabled by default) totally fucked my wifi stability, and disabling it fixed it to be smooth sailing!

bwDraco

@HornOKPlease Wat.

Tell NETGEAR about this. This needs to be fixed in a firmware update.

MU-MIMO has been on since day one on my R7800 and I have had no trouble at all.

Horn OK Please

puu.sh/ChcuU/428f4f4325.png

Online.net is part of Scaleway?

bwDraco

The other way around.

But a rebranding? That's interesting...

Huh. So they're changing their top-level brand to Scaleway.

Journeyman Geek

@HornOKPlease online is mostly dedis, scaleway is cheap VPSes

bwDraco

Absolute volume control would explain lower-than-expected volume. The maximum is 100%, and anything less than that would result in lower volume than if you directly connected the MP3 player to the headphones via the 3.5mm to 2.5mm cable (supplied with the headphones).

And losing MU-MIMO can hurt performance when you have lots of (newer) devices communicating at the same time.

2

A: How do MU-MIMO routers handle non-MU-MIMO devices?

Devices without MU-MIMO (called single-user MIMO, or SU-MIMO) will continue to communicate with the router in a round-robin fashion. This is formally called time-division multiple access (TDMA). Any MU-MIMO devices can communicate simultaneously on the same time slices, thereby increasing total t...